Betalactamase activity was studied in 142 non-tuberculosis mycobacteri
al strains. The distribution according to species was as follows: four
M. avium, 14 M. chelonae, 10 M. fortuitum, 53 M. gordonae 55 M. kansa
sii. The spectrum of hydrolysis of the betalactamases was screened usi
ng an acidimetric method and the characterization was performed by ana
lytical isoelectric focusing.